Fix SeekForPrev bug with Partitioned Filters and Prefix #5907
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siying
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@maysamyabandeh merged this pull request in 4e729f9. |
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Summary: Partition Filters make use of a top-level index to find the partition that might have the bloom hash of the key. The index is with internal key format (before format version 3). Each partition contains the i) blooms of the keys in that range ii) bloom of prefixes of keys in that range, iii) the bloom of the prefix of the last key in the previous partition. When ::SeekForPrev(key), we first perform a prefix bloom test on the SST file. The partition however is identified using the full internal key, rather than the prefix key. The reason is to be compatible with the internal key format of the top-level index. This creates a corner case. Example: - SST k, Partition N: P1K1, P1K2 - SST k, top-level index: P1K2 - SST k+1, Partition 1: P2K1, P3K1 - SST k+1 top-level index: P3K1 When SeekForPrev(P1K3), it should point us to P1K2. However SST k top-level index would reject P1K3 since it is out of range. One possible fix would be to search with the prefix P1 (instead of full internal key P1K3) however the details of properly comparing prefix with full internal key might get complicated. The fix we apply in this PR is to look into the last partition anyway even if the key is out of range. Pull Request resolved: #5907 Differential Revision: D17889918 Pulled By: maysamyabandeh fbshipit-source-id: 169fd7b3c71dbc08808eae5a8340611ebe5bdc1e
maysamyabandeh
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maysamyabandeh
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Summary: Partition Filters make use of a top-level index to find the partition that might have the bloom hash of the key. The index is with internal key format (before format version 3). Each partition contains the i) blooms of the keys in that range ii) bloom of prefixes of keys in that range, iii) the bloom of the prefix of the last key in the previous partition. When ::SeekForPrev(key), we first perform a prefix bloom test on the SST file. The partition however is identified using the full internal key, rather than the prefix key. The reason is to be compatible with the internal key format of the top-level index. This creates a corner case. Example: - SST k, Partition N: P1K1, P1K2 - SST k, top-level index: P1K2 - SST k+1, Partition 1: P2K1, P3K1 - SST k+1 top-level index: P3K1 When SeekForPrev(P1K3), it should point us to P1K2. However SST k top-level index would reject P1K3 since it is out of range. One possible fix would be to search with the prefix P1 (instead of full internal key P1K3) however the details of properly comparing prefix with full internal key might get complicated. The fix we apply in this PR is to look into the last partition anyway even if the key is out of range. Pull Request resolved: #5907 Differential Revision: D17889918 Pulled By: maysamyabandeh fbshipit-source-id: 169fd7b3c71dbc08808eae5a8340611ebe5bdc1e
maysamyabandeh
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merryChris
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Summary: Partition Filters make use of a top-level index to find the partition that might have the bloom hash of the key. The index is with internal key format (before format version 3). Each partition contains the i) blooms of the keys in that range ii) bloom of prefixes of keys in that range, iii) the bloom of the prefix of the last key in the previous partition. When ::SeekForPrev(key), we first perform a prefix bloom test on the SST file. The partition however is identified using the full internal key, rather than the prefix key. The reason is to be compatible with the internal key format of the top-level index. This creates a corner case. Example: - SST k, Partition N: P1K1, P1K2 - SST k, top-level index: P1K2 - SST k+1, Partition 1: P2K1, P3K1 - SST k+1 top-level index: P3K1 When SeekForPrev(P1K3), it should point us to P1K2. However SST k top-level index would reject P1K3 since it is out of range. One possible fix would be to search with the prefix P1 (instead of full internal key P1K3) however the details of properly comparing prefix with full internal key might get complicated. The fix we apply in this PR is to look into the last partition anyway even if the key is out of range. Pull Request resolved: facebook#5907 Differential Revision: D17889918 Pulled By: maysamyabandeh fbshipit-source-id: 169fd7b3c71dbc08808eae5a8340611ebe5bdc1e
merryChris
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Summary: This is the 3rd attempt after the revert of facebook#4020 and facebook#5895 The last bug is fixed facebook#5907 Pull Request resolved: facebook#5918 Test Plan: ``` make -j32 crash_test ``` Differential Revision: D17909489 Pulled By: maysamyabandeh fbshipit-source-id: 7dfb8cf998c2d295c86465dd21734593d277887e
merryChris
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Nov 18, 2019
Summary: Update history for the bug fix in facebook#5907 Pull Request resolved: facebook#5925 Differential Revision: D17952605 Pulled By: maysamyabandeh fbshipit-source-id: 609afcbb2e4087f9153822c4d11193a75a7b0e7a
yiwu-arbug
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Nov 26, 2019
Summary: Partition Filters make use of a top-level index to find the partition that might have the bloom hash of the key. The index is with internal key format (before format version 3). Each partition contains the i) blooms of the keys in that range ii) bloom of prefixes of keys in that range, iii) the bloom of the prefix of the last key in the previous partition. When ::SeekForPrev(key), we first perform a prefix bloom test on the SST file. The partition however is identified using the full internal key, rather than the prefix key. The reason is to be compatible with the internal key format of the top-level index. This creates a corner case. Example: - SST k, Partition N: P1K1, P1K2 - SST k, top-level index: P1K2 - SST k+1, Partition 1: P2K1, P3K1 - SST k+1 top-level index: P3K1 When SeekForPrev(P1K3), it should point us to P1K2. However SST k top-level index would reject P1K3 since it is out of range. One possible fix would be to search with the prefix P1 (instead of full internal key P1K3) however the details of properly comparing prefix with full internal key might get complicated. The fix we apply in this PR is to look into the last partition anyway even if the key is out of range. Pull Request resolved: facebook#5907 Differential Revision: D17889918 Pulled By: maysamyabandeh fbshipit-source-id: 169fd7b3c71dbc08808eae5a8340611ebe5bdc1e
yiwu-arbug
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Nov 26, 2019
Summary: Update history for the bug fix in facebook#5907 Pull Request resolved: facebook#5925 Differential Revision: D17952605 Pulled By: maysamyabandeh fbshipit-source-id: 609afcbb2e4087f9153822c4d11193a75a7b0e7a
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Apr 6, 2021
Summary: According to #5907, each filter partition "should include the bloom of the prefix of the last key in the previous partition" so that SeekForPrev() in prefix mode can return correct result. The prefix of the last key in the previous partition does not necessarily have the same prefix as the first key in the current partition. Regardless of the first key in current partition, the prefix of the last key in the previous partition should be added. The existing code, however, does not follow this. Furthermore, there is another issue: when finishing current filter partition, `FullFilterBlockBuilder::AddPrefix()` is called for the first key in next filter partition, which effectively overwrites `last_prefix_str_` prematurely. Consequently, when the filter block builder proceeds to the next partition, `last_prefix_str_` will be the prefix of its first key, leaving no way of adding the bloom of the prefix of the last key of the previous partition. Prefix extractor is FixedLength.2. ``` [ filter part 1 ] [ filter part 2 ] abc d ``` When SeekForPrev("abcd"), checking the filter partition will land on filter part 2 because "abcd" > "abc" but smaller than "d". If the filter in filter part 2 happens to return false for the test for "ab", then SeekForPrev("abcd") will build incorrect iterator tree in non-total-order mode. Also fix a unit test which starts to fail following this PR. `InDomain` should not fail due to assertion error when checking on an arbitrary key. Pull Request resolved: #8137 Test Plan: ``` make check ``` Without this fix, the following command will fail pretty soon. ``` ./db_stress --acquire_snapshot_one_in=10000 --avoid_flush_during_recovery=0 \ --avoid_unnecessary_blocking_io=0 --backup_max_size=104857600 --backup_one_in=0 \ --batch_protection_bytes_per_key=0 --block_size=16384 --bloom_bits=17 \ --bottommost_compression_type=disable --cache_index_and_filter_blocks=1 --cache_size=1048576 \ --checkpoint_one_in=0 --checksum_type=kxxHash64 --clear_column_family_one_in=0 \ --compact_files_one_in=1000000 --compact_range_one_in=1000000 --compaction_ttl=0 \ --compression_max_dict_buffer_bytes=0 --compression_max_dict_bytes=0 \ --compression_parallel_threads=1 --compression_type=zstd --compression_zstd_max_train_bytes=0 \ --continuous_verification_interval=0 --db=/dev/shm/rocksdb/rocksdb_crashtest_whitebox \ --db_write_buffer_size=8388608 --delpercent=5 --delrangepercent=0 --destroy_db_initially=0 --enable_blob_files=0 \ --enable_compaction_filter=0 --enable_pipelined_write=1 --file_checksum_impl=big --flush_one_in=1000000 \ --format_version=5 --get_current_wal_file_one_in=0 --get_live_files_one_in=1000000 --get_property_one_in=1000000 \ --get_sorted_wal_files_one_in=0 --index_block_restart_interval=4 --index_type=2 --ingest_external_file_one_in=0 \ --iterpercent=10 --key_len_percent_dist=1,30,69 --level_compaction_dynamic_level_bytes=True \ --log2_keys_per_lock=10 --long_running_snapshots=1 --mark_for_compaction_one_file_in=0 \ --max_background_compactions=20 --max_bytes_for_level_base=10485760 --max_key=100000000 --max_key_len=3 \ --max_manifest_file_size=1073741824 --max_write_batch_group_size_bytes=16777216 --max_write_buffer_number=3 \ --max_write_buffer_size_to_maintain=8388608 --memtablerep=skip_list --mmap_read=1 --mock_direct_io=False \ --nooverwritepercent=0 --open_files=500000 --ops_per_thread=20000000 --optimize_filters_for_memory=0 --paranoid_file_checks=1 --partition_filters=1 --partition_pinning=0 --pause_background_one_in=1000000 \ --periodic_compaction_seconds=0 --prefixpercent=5 --progress_reports=0 --read_fault_one_in=0 --read_only=0 \ --readpercent=45 --recycle_log_file_num=0 --reopen=20 --secondary_catch_up_one_in=0 \ --snapshot_hold_ops=100000 --sst_file_manager_bytes_per_sec=104857600 \ --sst_file_manager_bytes_per_truncate=0 --subcompactions=2 --sync=0 --sync_fault_injection=False \ --target_file_size_base=2097152 --target_file_size_multiplier=2 --test_batches_snapshots=0 --test_cf_consistency=0 \ --top_level_index_pinning=0 --unpartitioned_pinning=1 --use_blob_db=0 --use_block_based_filter=0 \ --use_direct_io_for_flush_and_compaction=0 --use_direct_reads=0 --use_full_merge_v1=0 --use_merge=0 \ --use_multiget=0 --use_ribbon_filter=0 --use_txn=0 --user_timestamp_size=8 --verify_checksum=1 \ --verify_checksum_one_in=1000000 --verify_db_one_in=100000 --write_buffer_size=4194304 \ --write_dbid_to_manifest=1 --writepercent=35 ``` Reviewed By: pdillinger Differential Revision: D27553054 Pulled By: riversand963 fbshipit-source-id: 60e391e4a2d8d98a9a3172ec5d6176b90ec3de98
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Summary: According to #5907, each filter partition "should include the bloom of the prefix of the last key in the previous partition" so that SeekForPrev() in prefix mode can return correct result. The prefix of the last key in the previous partition does not necessarily have the same prefix as the first key in the current partition. Regardless of the first key in current partition, the prefix of the last key in the previous partition should be added. The existing code, however, does not follow this. Furthermore, there is another issue: when finishing current filter partition, `FullFilterBlockBuilder::AddPrefix()` is called for the first key in next filter partition, which effectively overwrites `last_prefix_str_` prematurely. Consequently, when the filter block builder proceeds to the next partition, `last_prefix_str_` will be the prefix of its first key, leaving no way of adding the bloom of the prefix of the last key of the previous partition. Prefix extractor is FixedLength.2. ``` [ filter part 1 ] [ filter part 2 ] abc d ``` When SeekForPrev("abcd"), checking the filter partition will land on filter part 2 because "abcd" > "abc" but smaller than "d". If the filter in filter part 2 happens to return false for the test for "ab", then SeekForPrev("abcd") will build incorrect iterator tree in non-total-order mode. Also fix a unit test which starts to fail following this PR. `InDomain` should not fail due to assertion error when checking on an arbitrary key. Pull Request resolved: #8137 Test Plan: ``` make check ``` Without this fix, the following command will fail pretty soon. ``` ./db_stress --acquire_snapshot_one_in=10000 --avoid_flush_during_recovery=0 \ --avoid_unnecessary_blocking_io=0 --backup_max_size=104857600 --backup_one_in=0 \ --batch_protection_bytes_per_key=0 --block_size=16384 --bloom_bits=17 \ --bottommost_compression_type=disable --cache_index_and_filter_blocks=1 --cache_size=1048576 \ --checkpoint_one_in=0 --checksum_type=kxxHash64 --clear_column_family_one_in=0 \ --compact_files_one_in=1000000 --compact_range_one_in=1000000 --compaction_ttl=0 \ --compression_max_dict_buffer_bytes=0 --compression_max_dict_bytes=0 \ --compression_parallel_threads=1 --compression_type=zstd --compression_zstd_max_train_bytes=0 \ --continuous_verification_interval=0 --db=/dev/shm/rocksdb/rocksdb_crashtest_whitebox \ --db_write_buffer_size=8388608 --delpercent=5 --delrangepercent=0 --destroy_db_initially=0 --enable_blob_files=0 \ --enable_compaction_filter=0 --enable_pipelined_write=1 --file_checksum_impl=big --flush_one_in=1000000 \ --format_version=5 --get_current_wal_file_one_in=0 --get_live_files_one_in=1000000 --get_property_one_in=1000000 \ --get_sorted_wal_files_one_in=0 --index_block_restart_interval=4 --index_type=2 --ingest_external_file_one_in=0 \ --iterpercent=10 --key_len_percent_dist=1,30,69 --level_compaction_dynamic_level_bytes=True \ --log2_keys_per_lock=10 --long_running_snapshots=1 --mark_for_compaction_one_file_in=0 \ --max_background_compactions=20 --max_bytes_for_level_base=10485760 --max_key=100000000 --max_key_len=3 \ --max_manifest_file_size=1073741824 --max_write_batch_group_size_bytes=16777216 --max_write_buffer_number=3 \ --max_write_buffer_size_to_maintain=8388608 --memtablerep=skip_list --mmap_read=1 --mock_direct_io=False \ --nooverwritepercent=0 --open_files=500000 --ops_per_thread=20000000 --optimize_filters_for_memory=0 --paranoid_file_checks=1 --partition_filters=1 --partition_pinning=0 --pause_background_one_in=1000000 \ --periodic_compaction_seconds=0 --prefixpercent=5 --progress_reports=0 --read_fault_one_in=0 --read_only=0 \ --readpercent=45 --recycle_log_file_num=0 --reopen=20 --secondary_catch_up_one_in=0 \ --snapshot_hold_ops=100000 --sst_file_manager_bytes_per_sec=104857600 \ --sst_file_manager_bytes_per_truncate=0 --subcompactions=2 --sync=0 --sync_fault_injection=False \ --target_file_size_base=2097152 --target_file_size_multiplier=2 --test_batches_snapshots=0 --test_cf_consistency=0 \ --top_level_index_pinning=0 --unpartitioned_pinning=1 --use_blob_db=0 --use_block_based_filter=0 \ --use_direct_io_for_flush_and_compaction=0 --use_direct_reads=0 --use_full_merge_v1=0 --use_merge=0 \ --use_multiget=0 --use_ribbon_filter=0 --use_txn=0 --user_timestamp_size=8 --verify_checksum=1 \ --verify_checksum_one_in=1000000 --verify_db_one_in=100000 --write_buffer_size=4194304 \ --write_dbid_to_manifest=1 --writepercent=35 ``` Reviewed By: pdillinger Differential Revision: D27553054 Pulled By: riversand963 fbshipit-source-id: 60e391e4a2d8d98a9a3172ec5d6176b90ec3de98
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Partition Filters make use of a top-level index to find the partition that might have the bloom hash of the key. The index is with internal key format (before format version 3). Each partition contains the i) blooms of the keys in that range ii) bloom of prefixes of keys in that range, iii) the bloom of the prefix of the last key in the previous partition.
When ::SeekForPrev(key), we first perform a prefix bloom test on the SST file. The partition however is identified using the full internal key, rather than the prefix key. The reason is to be compatible with the internal key format of the top-level index. This creates a corner case. Example:
When SeekForPrev(P1K3), it should point us to P1K2. However SST k top-level index would reject P1K3 since it is out of range.
One possible fix would be to search with the prefix P1 (instead of full internal key P1K3) however the details of properly comparing prefix with full internal key might get complicated. The fix we apply in this PR is to look into the last partition anyway even if the key is out of range.